Complete graph conjecture for inner-core electrons: homogeneous index case

The complete graph conjecture that encodes the inner-core electrons of atoms with principal quantum number n >or= 2 with complete graphs, and especially with odd complete graphs, is discussed. This conjecture is used to derive new values for the molecular connectivity and pseudoconnectivity basis indices of hydrogen-suppressed chemical pseudographs. For atoms with n = 2 the new values derived with this conjecture are coincident with the old ones. The modeling ability of the new homogeneous basis indices, and of the higher-order terms, is tested and compared with previous modeling studies, which are centered on basis indices that are either based on quantum concepts or partially based on this new conjecture for the inner-core electrons. Two similar algorithms have been proposed with this conjecture, and they parallel the two "quantum" algorithms put forward by molecular connectivity for atoms with n > 2. Nine properties of five classes of compounds have been tested: the molecular polarizabilities of a class of organic compounds, the dipole moment, molar refraction, boiling points, ionization energies, and parachor of a series of halomethanes, the lattice enthalpy of metal halides, the rates of hydrogen abstraction of chlorofluorocarbons, and the pED(50) of phenylalkylamines. The two tested algorithms based on the odd complete graph conjecture give rise to a highly interesting model of the nine properties, and three of them can even be modeled by the same set of basis indices. Interesting is the role of some basis indices all along the model.     

Thermodynamic investigation of the state of water adsorbed by carbonaceous adsorbents

The state of water adsorbed on active carbons and canal soot was studied using the “chemical potential—entropy—temperature” diagram. In the range of the relative pressures from 0.174 to 1, the state of adsorbed water is similar to the state of a stretched liquid. The molar volume, heat of evaporation, and surface tension of stretched water were calculated at different relative pressures. Near the spinodal, the molar volume of stretched water is 25% higher, and the surface tension is considerably lower compared to water. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 464–468, March, 1997.     

Inverse relaxation-model and relation to recovery internal friction

Inverse relaxation is studied for hard elastic polypropylene (HEPP), rubber and non-elastic polypropylene. The results show that contractive stress, stress, and internal friction are three essential factors related to the phenomenon. A three-element model in which each element has a definite meaning is proposed to describe this phenomenon. The results also show that, in the first cyclic deformation, relaxation time increases with the increase of recovery for all the materials, which indicates that recovery viscosity increases with the increase of recovery, but the stress rising amplitude (SRA) of inverse relaxation has a maximum in the recovery range. Analysis indicates that SRA equals recovery internal friction (RIF) for ideal material in which stress is solely a function of strain, independent of paths, and approximately equals RIF for non-ideal material at a given strain. From this principle it is found that the order of the work counteracted by RIF for the four materials is the same as that of their second hysteresis loop, and the RIF of HEPP has a sudden increase at the later recovery range.     

Conformational analysis of [Met5]-enkephalin: Solvation and ionization considerations

[Met5]-Enkephalin has the sequence Tyr-Gly-Gly-Phe-Met. Only the extended conformation of the peptide has been observed by X-ray crystallography. Nuclear magnetic resonance spectroscopy supports the presence of a turn at Gly 3 and Phe 4 in dimethyl sulfoxide. In this study, the peptide conformational states and thermodynamic properties are understood in terms of ionization state and solvent environment. In the calculation, final conformations obtained from multiple independent Monte Carlo simulated annealing conformational searches are starting points for molecular dynamics simulations. In an aqueous environment given by the use of solvation free energy and the zwitterionic state, dominant structural motifs computed are G-P Type II bend, G-G Type II bend, and G-G Type I bend motifs, in order of increasing free energy. In the calculation of the peptide with neutral N- and C-termini and solvation free energy, the extended conformer dominates (by at least a factor of 2.5), and the conformation of another low free energy conformer superimposes well on the pharmacophoric groups of morphine. Neutralization of charge and solvation induce and stabilize the extended conformation, respectively. A mechanism of inter-conversion between the extended conformer and three bent conformers is supported by /-scatter plots, and by the conformer relative free energies. An estimate of the entropy change of receptor unbinding is 8.3 cal K-1 mol-1, which gives rise to a -2.5 kcal/mol entropy contribution to the free energy of unbinding at 25 °C. The conformational analysis methodology described here should be useful in studies on short peptides and flexible protein surface loops that have important biological implications.     

共聚高分子混合物的分子热力学模型

以硬球链流体的分子热力学模型为基础 ,引入方阱位能相互作用的贡献 ,建立了共聚高分子混合物的分子热力学模型 .模型中具有物理意义的链节参数 (链节数、链节直径和链节间的相互作用能 )由纯物质的pVT关系拟合得到 ,而用来校正交叉作用能和交叉碰撞直径的可调参数需由液液平衡的实验数据回归得到 .采用了相对简单的处理方法来确定这些可调参数 .对所选共聚高分子混合物的共存曲线、互溶窗和互溶图等相行为的关联结果令人满意 .     

K/Ru(10ī0)表面上的CO-4a1轨道对称性确定

用同步辐射角分辨偏振紫外光电子谱对Ｋ／Ｒｕ（１０１０）面上吸附分子轨道的对称性测量发现：结合能在１１、．２ｅＶ的ＣＯ－４ａ１（４σ）分子轨道对ｓ偏振光（在沿〈１２１０〉的人射面）是禁戒的。结果表明由于Ｋ的强烈影响,ＣＯ的分子轨道重新排列（ｓＰ＾２杂化）。依据选择定则和分子轨道的对称性６说明,ｓｐ＾２再杂化的ＣＯ分子吸附的桥位取向是〈１２１０〉晶向。     

煤焦在燃烧过程中孔隙结构变化的模拟

煤焦在燃烧过程中的物理特性，如比表面积和孔径分布会发生连续变化，直接测量煤焦在燃烧过程中的孔隙结构变化很困难，但可以通过合适的数学模型来观察，二维的圆柱孔模型已大量用来对煤焦气化与燃烧过程中表面积和孔隙结构的变化进行模拟，这个模型把孔隙分成两大部分－－大孔与小孔，因为小孔构成比表面的绝大部分，所以在反应过程中比表面积的变化可以由单一小孔模型来拟合，本文采用了用Ｔｓｅｎｇ和Ｅｄｇａｒ提出的孔模型对几     

冠醚化Schiff 碱配合物金属胶束催化BNPP水解动力学

研究了两种新的冠醚化Schiff 碱过渡金属配合物与表面活性剂Brij35(聚氧乙烯(23)十二烷基醚)形成的金属胶束对BNPP（对硝基苯酚磷酸二酯）的催化水解反应. 探讨了催化反应机理, 建立了一种金属胶束催化BNPP水解的动力学数学模型; 计算了模拟酶催化反应的相关参数和表观活化能. 结果表明, 此类金属胶束作为模拟水解金属酶对BNPP水解反应表现出良好的催化活性.     

ADSORPTION OF 2,4-D ON MODIFIED HYPERCROSSLINKED POLYSTYRENE （NDA-99） AND XAD-4 RESIN

The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent (NDA-99) modified by dimethylamine group as well as a nonionic macroporous adsorbent (XAD-4). The Langmuir and Freundlich isotherm models were employed to fit the experimental data to describe adsorption mechanism. It shows that NDA-99 resin exhibits an adsorption affinity for 2,4-D higher than XAD-4 resin owing to its exceptional micropore structure and the amine group of the hypercrosslinked matrix.Further studies indicate that the hydrogen bonding interaction and the stronger π-π conjugation play a significant role in the course of the adsorption of 2,4-D on NDA-99 resin, which is in agreement with the IR spectroscopic results and the △E values of HOMO (the highest occupied molecular orbit) of adsorbent and LUMO (the lowest unoccupied molecular orbit) of adsorbate calculated from the MINDO/3 model.